265 



In order to minimise these defects it has been proposed to conduct 

 the first part of the manufacture of citric acid on the spot, and produce 

 citrate of lime. This idea has been afloat for upwards of thirty years : 

 in the last few years it appears to have been acted upon with some 

 degree of success : in fact it is stated that this article has entirely taken 

 the place of shipments of concentrated lemon juice from Palermo. 



I am unable to ascertain the actual quantities imported into Eng- 

 land and other European countries, but Messrs. Gillespie Bros. & Oo. 

 of New York, who have made enquiries on the subject,inform me that 

 the imports into the United States for the past few years have been as 

 follows : — 



Years. 



Quantities. 



Values. 



Yalue per unit of quantity 





Lbs. 



8. 





1887 



42,558 



6,004 



.14 



1889 



47,890 



8,569 



.18 



1891 



28,358 



4,337 



.15 



1892 



220,468 



30.459 



.14 



1893 



629,739 



75,271 



.12 



1894 



443,891 



52,137 



.12 



1895 



608,214 



59,458 



.10 



1896 



668,106 



66,388 



.097 



1897 



496,291 



42,090 



.085 



1898 



1,026,467 



84,789 



.082 



Up to the present this appears to have been entirely produced in 

 Italy or Sicily, none having been imported from the West Indies. 



The preparation of citrate of lime is the first step in the manu- 

 facture of citric acid from lemon or lime juice. We are well aware 

 that when the juice of the sugar cane is concentrated to a suflB.- 

 cient degree, the active principle, cane sugar, separates out in the form 

 of crystals ; the active principle of lemon or lime juice, citric acid, will 

 not separate in a cry st aline form when the juice is simply concentrated, 

 owing to the presence in the juice of a large quantity of gummy or 

 pectic impurities. In order to overcome this difficulty the citric acid i» 

 brought into combination with lime, the citrate of lime thus formed 

 being insoluble in water can be separated from the gummy matters 

 which remain dissolved. In order to effect this the juice is neutralised 

 with chalk, the resulting citrate of lime is allowed to subside and finally 

 separated by straining by means of linen or canvas. The resulting cit- 

 rate may now be dried for shipment or be treated with sulphuric acid 

 for the manufacture of citric acid. 



Simple as the above process appears, there are many practical difficul- 

 ties, particularly in the preparation of the dried citrate for export. 



In the first place the chalk employed must be of very fine quality^ 

 free from magnesium salts and from more than a trace of iron, alumina, 

 and phosphates. Either of these impurities exercises a prejudicial 

 action at one or other stage of the manufacturing process. Again the 

 chalk must be of such a quality that it can be readily mixed into st 

 cream with water, it must be free from lumps. In order to obtain 

 chalk of proper quality English or French levigated whiting was for a 

 long time imported into Italy and Sicily for the preparation of citrate 



